Process of shrink-proofing goods containing keratinous fibers



United States Patent Ofi 3,476,502 Patented Nov. 4, 1969 3,476,502 PROCESS OF SHRINK-PROOFING GOODS CON- TAINING KERATINOUS FIBERS Walter E. Bill, Pittsburgh, Pa., and George L. Payet, Barberton, Ohio, assignors to PPG Industries, Inc., Pittsburgh, Pa., a corporation of Pennsylvania No Drawing. Filed May 6, 1965, Ser. No. 453,822

Int. Cl. D06m 3/02, 3/06, 3/08 US. Cl. 8127.6 13 Claims ABSTRACT OF THE DISCLOSURE This invention relates to an improved method for the chemical shrinkproofing of fabrics containing keratinous fibers. It more specifically relates to an improved method of shrinkproofing wool and textiles which contain wool.

Fabrics which contain keratinous fibers, such as wool, exhibit a considerable tendency to shrink when washed in warm or hot aqueous baths. This tendency is particularly noticeable when the washing or soaking is accompanied by agitation. Shrinkage is apparently due to tangling of the fibers. Once the fibers are tangled, they are held in a tangled position by interlocking of surface scales on the fibers. With repeated washings, the fibers continue to tangle tighter and tighter until the fabric becomes a thick felt. As the fibers tangle, the area of the cloth becomes diminished. Wool cloth, for example, may shrink sufficiently to reduce its total area to 50 percent or less of its original area.

By keratinous fiber, as used herein and in the accompanying claims, is meant generally the hair of any animal. The term includes blends of such hair with other natural or synthetic fibers. Usually the keratinous fibers treated in accordance with this invention predominate in one or an admixture of various kinds of Wool. Hair from other animals, for example, the goat and camel families are also responsive to treatment according to this invention. The invention may be practiced on goods containing the fibers in any form, i.e., as raw hair, as yarn, as fabric, or as textiles such as sweaters or hosiery. Such application may be made after the goods have been dyed. Generally, for use herein, the animal hair is in the form of cloth or textiles rather than in the form of fleece or attached to the hide. This invention is particularly applicable to woven or knit goods. In other embodiments, the invention is conveniently applied to yarn.

A variety of chemical shrinkproofing treatments are currently available. These shrinkproofing treatments generally involve removing or stripping the surface scales from the fibers. In this way, a smoother fiber is produced. Although these smoother fibers may become tangled, they are free to untangle and return to approximately their original position. Shrinkproofing has generally been accomplished by treatment of the fabric with a variety of chemicals which tend to attack the SS linkages in the fiber.

All presently available chemical shrinkproofing methods have inherent disadvantages. For example, the potassium permanganate-brine process results in deposition on the fibers of dark colored manganese dioxide. Treatment with sodium hypochlorite causes chlorination of wool resulting in yellowing.

The present invention provides a new chemical shrinkproofing treatment for keratinous fibers and fabrics. According to the instant invention, suitable shrinkproofing is obtainable without imparting objectionable colors to the treated material. The resultant fabric is soft to the touch. In the practice of the instant invention, the goods are first treated in aqueous media in the presence of hydrogen peroxide and acetic anhydride. The goods are then treated in aqueous media in the presence of a bisulfite. The treatment is economical and convenient in application. Goods treated in accordance with the present invention exhibit uniform dye acceptance.

Preparatory to the chemical treatment provided by the instant invention, the goods are usually washed or scrubbed to remove foreign bodies such as dirt, grime, Wax, wool grease, animal oils, misc. oils, etc. For this purpose, any effective procedure may be employed. Usually it is sufiicient to wash the goods in a warm, typically between about F. and F., aqueous medium containing small amounts of soap. When the goods are particularly dirty, mild alkalies such as ammonium hydroxide or some times stronger alkali such as sodium carbonate may be employed. Usually from about 5 to about 45 minutes in a bath at a bath-to-goods ratio of at least about 20:1 cleans the goods sufiiciently for treatment in accordance with this invention. After Washing, the goods are desirably rinsed and directly transferred to the shrinkproofing treatment or they may be dried and treated at a subsequent time.

As used herein and in the claims, the bath-to-goods ratio refers to the ratio of the weight of the bath, including all dissolved components, to the weight of the dry, clean goods. By dry is meant dry to the touch. the weight of dirt, grime, oil, etc., which may be present on the dry goods is usually negligible in comparison to the weight of the goods.

In accordance with the present invention, the goods are first treated in a bath in the presence of hydrogen peroxide and acetic anhydride. The bath generally comprises water to which the peroxide, anhydride, and any other components of the bath are added, either before or after the goods are introduced to the bath. The material is then removed from this first bath and treated in a second bath in the presence of a bisulfite. Preferably the material is rinsed subsequent to the hydrogen peroxideacetic anhydride treatment and prior to the bisulfite after-treatment.

The hydrogen peroxide bath typically contains from about 0.1 to about 1.5 percent, preferably about 0.3 to about 0.5 percent by weight, basis the weight of the water in the bath, hydrogen peroxide. The H 0 is based on anhydrous H 0 although this chemical is usually added in aqueous solutions containing either 35 or 50 percent by weight H 0 Prior to the addition of the acetic anhydride, it is desirable to include in the bath a small amount of an ammonium base, such as NH OH or organic ammonium base or amine. The ammonium additive should be readi- 1y removable from the treated goods. Ammonium hydroxide is particularly useful because of its low cost and because it readily volatilizes from the treated goods. Typically about 0.05 to about 0.2 percent by weight on the aforesaid basis of concentrated ammonium hydroxide solution added to the hydrogen peroxide bath produces satisfactory results. The pH of the bath may drop well below 7, sometimes as low as about 3 or less upon the addition of acetic anhydride. Comparable amounts of amines are employable. Of particular usefulness, for example, are monoethanol amine, triethanol amine and pyridine.

When the fabric is introduced to the bath dry, a small quantity of wetting agent, sufiicient to facilitate ready wetting of the fabric, is also preferably added. Nonionic Wetting agents are preferred because it is desired to avoid chemical reaction between the wetting agent and the active components of the treating solution. Alkyl aryl polyether alcohols (such as that marketed under the trade name Triton X-100) have been found most advantageous. Generally about 0.1 to about 0.3 percent by weight, basis the water in the bath, of the wetting agent is sufiicient.

It is preferable to include the goods to be treated in the treating bath prior to addition of the acetic anhydride. The acetic anhydride is preferably added in several increments although it is possible to blend the entire required amount of acetic anhydride into the bath at one time. Sufiicient acetic anhydride is employed to effect the decomposition of substantially all of the hydrogen peroxide in the bath. Usually, at least 0.05 percent by weight, based on the weight of the water in the bath of acetic anhydride, is required to efiect suitable decomposition. It has been found most advantageous to divide the required amount of acetic anhydride into a plurality, for example, about 2 to about -6 approximately equal proportions. More than 6 additions unduly extend the time required for treatment. These divided proportions are then added to the bath under constant agitation at intervals ranging from about 3 to about 8 minutes. After the last addition of anhydride, the treatment is continued under agitation for a few, typically from about to about 10 minutes. Although excess acetic anhydride is tolerable, it is economically desirable to employ the minimum effective amount. Thus, amounts in excess of about 1 percent by weight are rarely employed.

After completion of the peroxide treatment, the goods are removed from the bath. They are then washed or rinsed for about 30 to about 60 minutes to effect substantially complete removal of all the treating chemicals. Any convenient washing or rinsing procedure suitable for removing the treating chemicals from the goods is employable. Agitating the goods in a clear water bath for about 30 minutes at about 80 F. to about 120 F. has proven adequate. Following the rinsing step, the materials are usually introduced directly to the after-treatment. It is, of course, within contemplation that the clamp goods be dried prior to the after-treatment.

The quantities of the treating baths are conveniently related to the goods being treated. Thus, it has been found for the purpose of this invention that the bathto-goods ratio is preferably from about 5:1 to about 40:1. A bath-to-goods ratio of less than 5:1, although employable, usually fails to provide suflicient liquid to contact the goods uniformly. Bath-to-goods ratios of higher than 40:1 generally necessitate the use of oversized equipment. Thus, although any bath-to-goods ratio sutficient to provide uniform contact of the liquids with the goods is employable, ratios of between about :1 to about 25:1 are usually most convenient. A bath-togoods ratio of :1 has been found to give consistently good results. Any convenient bath temperature, for example, about 80 F. to about 140 F., preferably about 110 F. to about 120 F., is employable.

- The treated goods must be after-treated with a bisulfite bath. Any alkali metal, i.e., sodium, potassium, lithium, rubidium or cesium bisulfite, is employable. Other bisulfites, e.g., alkaline earth metal bisulfite are often employable although these bisulfites, particularly those of calcium and barium, may form insoluble precipitates under the bath conditions employed. The term bisulfite as used herein and in the claims includes bisulfites such as NaHSO and meta-bisulfites such as Na S O The sodium salts are usually preferred because of their low cost. The bisulfite bath comprises water to which an appropriate amount of bisulfite as herein defined is added. For economic reasons, it is desirable to use a minimum amount of bisulfite. It has been found in the practice of this invention that an aqueous bath containing at least about 0.2

percent by weight of the bisulfite, based on the weight of the water in the solution, is required to satisfactorily after-treat most goods shrinkproofed in accordance with this invention. Baths containing in excess of about 2 percent by weight bisulfite are rarely required. Most fabrics are sufficiently after-treated with solutions containing between about 0.3 to about 1, usually between about 0.5 to about 0.8 percent by weight sodium bisulfite. Comparable amounts of other bisulfites are employable, e.g., about 0.4- to about 0.6 percent by weight sodium meta-bisulfite usually sufilciently after-treats most fabrics. The precise quantity of bisulfite required depends on the nature of the fabric being treated.

The bisulfite after-treatment is conveniently effected by agitating the material in an aqueous bath with a bathto-goods ratio comparable to those useful in the peroxide bath. Typically 25 to 35, rarely more than 50, usually at least about 20 minutes residence gives satisfactory aftertreatment. Any convenient bath temperature, for example, about F. to about 140 F., preferably about F. to about F. is employable, The bath temperatures employed in any of the baths taught by this invention should be below a temperature harmful to the goods. Following the bisulfite after-treatment, the materials are again rinsed and dried. The goods may be forwarded to a dyeing step when dry or while still wet.

The invention will be more fully understood with reference to the following examples.

Example I A 50 percent wool 50 percent worsted fabric was cut into squares 24 inches on one side and pre-marked three times across both the warp and the filling with black marks 18 inches apart. The selvage of the fabric was left on one side of the square to insure proper identification of the warp and filling.

The samples were treated in peroxide baths as indicated in Table I. The bath was maintained at 120 F. The bathto-goods ratio was about 20:1. After gently agitating the samples for five minutes, the first of four additions of acetic anhydride was added. The three remaining additions were made at five minute intervals. The total amount of acetic anhydride (the sum of four equal additions) is indicated in the table. The samples were kept in the bath ten minutes following the last addition of acetic anhydride for a total treating time of thirty minutes. The samples were gently agitated during their entire residence in the bath.

The samples were removed from the bath and washed in running water at room temperature for thirty minutes. All samples were treated in the peroxide baths and allowed to air dry.

The treated samples were then given the bisulfite aftertreatments recorded in Table I. The after-treatments consisted of gently agitating the samples in a bath containing the respective amounts of sodium meta-bisulfite. A 20:1 bath-to-goods ratio was employed. The goods were removed from the after-treatment bath, washed in running water at room temperature for thirty minutes, extracted and air-dried.

Afer drying, the goods were exposed to ambient conditions for at least four hours. The samples were measured to determine the shrinkage obtained during treatment. The shrinkage during treatment, i.e., the change in area based on the black marks, is reported in Table I. The samples were then remarked with red marks 18 inches apart across both the warp and the filling.

The samples were placed in a 0.1 percent solution of nonionic wetting agent. The solution at the start of the test was 100 F. and was allowed to cool throughout the test period. The samples remained in the solution for a minimum of four hours. They were then removed, extracted and air dried on a horizontal surface. Once dry they were conditioned by exposure to ambient temperature and humidity for at least four hours. The red marks were remeasured- Relaxation shrinkage, the percent change in area based on the red marks, is reported in Table I.

Total shrinkage was determined by washing the test samples six consecutive times in a Maytag washing machine Model A-500 under the following conditions:

Water (distilled) Temperature F 100:2 Setting, low gal 11.5 Washing time ..minutes.. 14 Agitation Regular Ivory Flakes g 50 Sample g 1500 TABLE I tests were run on two hose. The results are reported in Table II:

Although acetic anhydride is the preferred chemical used to decompose hydrogen peroxide for shrinkproofing wool in accordance with this invention, a number of other compounds are employed. Thus, in general, acids or the corresponding anhydrides, when such anhydrides exist, are employable, where the acid is a mono-carboxylic acid having the general formula R-COOlI-I where R is an alkyl group having 1 to 5 carbon atoms, or a dicarboxylic acidhaving the general formula HOOC-RCOOH where R is an alkylene group having 2 to 10 carbon atoms, or an aromatic dicarboxylic acid having the general formula Ar--(COOH) where Ar is an aromatic group having 6 to 12 carbon atoms. For example, formic or oxalic acid may be used. Maleic, diphthalic, isophthalic [Shrinkage of Wool-Worsted Fabrics After shrinkproofing With Hydrogen Peroxide and Sodium Metabisulfite] Relax- Shrinkage, Area Total Shrinkage, Percent ation Peroxide Bath, Percent Bisulfite Bath, shrinkwashings N32S7O5, Perage, Sample H 0 NHlOH T-X-IOO 4 A010 cent (O.W.G.) Percent 1st 2d 3d 4th 5th 6th 1. 0 0. 1 0.1 05 2.0 +2.80 5. 72 19. 47 33. 0t) 41. 59 53. 11 55. 15 1. 0 0. 1 U. 1 05 5. 0 +3. 7. 71 20.15 41. 92 50. 70 53. 24 1. 0 0. 1 0.1 05 20.0 +1.39 11.96 26. 52 34. 38 45. 27 52.10 52.95 1. 0 0. l 0. 1 0. 5 2.0 +2. 34 +2.56 +1.17 +1.38 0.73 2. 83 9. 27 1. 0 0.1 0. 1 0. 5 5.0 +3.02 +4. 49 +3. 32 +4. 65 +3. 45 +1.12 +0. 17 1. 0 0.1 0. 1 0. 5 7. 5 +2.79 +3. 76 +3.08 +4.65 +2.99 +3.10 +0.14 1. 0 0. 1 0. l 0. 5 10. 0 +2. 12 +4. +2. 57 +2. 79 +2. 77 +2. 27 +2. 17 1. 0 0.1 0. 1 0. 5 15.0 +1. 83 +4.20 +2. 28 +2.33 +2.02 0.09 +2. 46 1. 0 0.1 0. l 0. 5 20. 0 +1. 8 +3. 25 +1. 67 +0.22 0. 69 2. 31 6. 62 1. 0 0.1 0. 1 0. 5 +3. 52 9.31 16. 32 24. 70 35. 72 44. 98 49. 55 28. 99 41. 44 53. 38 61. 25 64. 84 65.95

1 24.3 percent sodium sulfate, based on the total weight of the bath.

9 Relaxation shrinkage indicates a physical strain on the fabric due to processing and is not indicative of the potential shrinkage characteristics of the fabric.

3 Felting shrinkage is determined by taking the algebraic difference of total shrinkage and relaxation shrinkage. 4 Triton X-100, a commercial alkyl aryl polyether alcohol wetting agent.

Example II Eleven pounds of 90 percent wool-l0 percent nylon hosiery were scoured using a bath-to-goods ratio of 19.8:]. with the solution containing:

Percent Tetrasodium pyrophosphate 0.75 Soap 0.10

Percent H 0 percent) 1.0 NH OH (30 percent NH 0.1 Triton X100 0.1

The hose were agitated in the solution at a bath-to-goods ratio of about 20:1 for five minutes at 120 F. Then, 0.5 percent acetic anhydride was added to the bath in four equal portions at five minute intervals. After the last addition of acetic anhydride, agitation was continued at 120 F. for ten minutes, making a total of thirty minutes of processing time. One cold water rinse was given for five minutes.

The hose was then treated in an aqueous solution containing 7.0 percent O.W.G. of sodium meta-bisulfite. The hose were agitated in the solution at a bath-to-goods ratio of about 20:1 for thirty minutes at 120 F. The hose were rinsed for five minutes at 115 F. Shrinkage or sebacic acids or their anhydrides may also be employed. The acid or anhydride should have at least 0.1 percent, preferably 0.5 or more percent solubility in the aqueous bath in which it is a component.

Although the instant invention has been described with reference to certain specific details of particular embodiments thereof, it is not intended thereby to limit the scope of the invention except insofar as these specific details are recited in the appended claims.

What is claimed is:

1. The process of shrinkproofing goods containing keratinous fibers which comprises treating said goods in a bath comprising an aqueous solution of hydrogen peroxide and adding to said aqueous solution, in an amount at least sufficient to decompose the hydrogen peroxide, a member selected from he group consisting of the acids and the corresponidng anhydrides, when such anhydrides exist, where the acid is selected from the group consisting of (1) mono-carboxylic acids having the general formula R-COOH where R is an alkyl group having 1 to-5 carbon atoms, (2) dicarboxylic acids having the general formula HOOC-R-COOH where R is an alkylene group having 2 to 10 carbon atoms, and (3) aromatic dicarboxylic acids having the general formula Ar(COOH) where Ar is an aromatic group having 6 to 12 carbon atoms, and further treating said goods With the resulting solution, and then treating said goods in a bath comprising an aqueous solution of a bisulfite.

2. The process of claim 1 wherein an ammonium base is present in the first named aqueous solution.

3. The process of claim 2 wherein the ammonium base is selected from the group consisting of ammonium hydroxide, mono-ethanol amine, triethanol amine, and pyridine.

4. The method of claim 2 wherein the bisulfite is selected from the group consisting of alkali metal bisulfites and meta-bisulfites.

5. The process of shrinkproofing goods containing keratinous fibers which comprises immersing said goods in a bath comprising an aqueous solution containing 0.1 to 1.5 percent hydrogen peroxide and 0.05 to 0.2 percent ammonium hydroxide and then adding at least 0.05 percent acetic anhydride and immersing the goods in the resulting solution, rinsing the goods with water, and then immersing said goods in a bath comprising an aqueous solution of at least 0.2 percent of a bisulfite.

6. The method of claim 5 wherein the bisulfite is selected from the group consisting of sodium bisulfite and sodium meta-bisulfite.

7. The method of claim 5 wherein a non-ionic wetting agent is present in the first named bath.

8. The method of claim 5 wherein the acetic anhydride is added to the peroxide bath in a plurality of spaced increments.

9. The process as defined in claim 5 wherein the firstmentioned bath, comprising an aqueous solution of hydrogen peroxide and ammonium hydroxide, further includes sodium sulfate.

10. The process as defined in claim 5 wherein the bath-to-goods ratio in the first and second-mentioned baths is between 5:1 and 40:1 and wherein the goods are treated in the first-mentioned bath for between 11 and 58 minutes at a temperature of between 80 F. and 140 F. and then treated in the second-mentioned bath for between 20 and 50 minutes at a temperature of between 80 F. and 140 F.

11. The process as defined in claim 5 wherein the bath-to-goods ratio in the first and second-mentioned baths is between 15:1 and 25:1 and wherein the tem- 8 perature of said baths is in the range of F. and F.

12. A process of shrinkproofing goods containing keratinous fibers which comprises immersing said goods in a bath comprising an aqueous solution of hydrogen peroxide and ammonium hydroxide, and further immersing said goods in a solution prepared by the addition to said bath of a member selected from the group consisting of formic, acetic, oxalic, maleic, diphthalic, isophthalic, and sebacic acids and the anhydrides of said acids, when said anhydrides exist, said member being added in an amount at least sufiicient to decompose the hydrogen peroxide, then immersing said goods in a bath comprising an aqueous solution of a bisulfite.

13. A process for reducing the tendency of goods containing keratinous to shrink which comprises immersing said goods in an aqueous solution containing sodium sulfate, 0.3 to 0.5 percent hydrogen peroxide and 0.05 to 0.2 percent ammonium hydroxide and then adding 0.05 to 1.0 percent acetic anhydride to the solution in a plurality of spaced increments while agitating the solution, removing the goods from the solution, washing the goods with water, immersing the goods in a second aqueous solution containing 0.3 to 1.0 percent of a bisulfite, removing the goods from the second solution, washing the goods in water, and drying the goods.

References Cited UNITED STATES PATENTS 2,382,632 8/ 1945 Hessel et a1. 8-127.6 2,649,357 8/1953 Happey et al. 8127.6 X 3,097,913 7/1963 Von Bergen et a1 8128 RICHARD D. LOVERING, Primary Examiner US. Cl. X.R. 8127.5, 128 

